Conventionally, a power supply system that includes a plurality of fuel cells and that supplies power to loads has been available. In such a power supply system, the total power supply capability thereof can be given by the total of power generation capabilities of the individual fuel cells.
A load having a smaller demand than the total power supply capability is selected and the load is connected to the power supply system. By setting the total power supply capability of the power supply system relatively higher than the demand of the loads, the power supply system can supply power to the loads stably.
The total power supply capability of the known power supply system is determined from a power generation capability at the time of installation of individual fuel cells. As a result, it is difficult to know the current total power supply capability of the power supply system. For example, even when the power generation capability decreases due to deterioration of the fuel cells, the total power supply capability of the power supply system is recognized as a value that is the same as that at the time of installation.
Consequently, when time has elapsed after the installation of the power supply system and the power generation capability of the fuel cells decreases, intended generation power may not obtained, thereby resulting in an insufficient power to be supplied to the loads. As a result, it has been difficult to supply power to the loads stably. In addition, it has been difficult to recognize a surplus-power generation capability of the power supply system.
Accordingly, an object of the present invention is to overcome such problems.